Epitaxial Growth of an Organic p–n Heterojunction: C₆₀ on Single-Crystal Pentacene

Designing molecular p–n heterojunction structures, i.e., electron donor–acceptor contacts, is one of the central challenges for further development of organic electronic devices. In the present study, a well-defined p–n heterojunction of two representative molecular semiconductors, pentacene and C₆₀, formed on the single-crystal surface of pentacene is precisely investigated in terms of its growth behavior and crystallographic structure. C₆₀ assembles into a (111)-oriented face-centered-cubic crystal structure with a specific epitaxial orientation on the (001) surface of the pentacene single crystal. The present experimental findings provide molecular scale insights into the formation mechanisms of the organic p–n heterojunction through an accurate structural analysis of the single-crystalline molecular contact